This invention relates generally to catheters, and particularly, to intravascular catheters for use in percutaneous transluminal coronary angioplasty (PTCA) or the delivery of stents.
In percutaneous transluminal coronary angioplasty (PTCA) procedures, a guiding catheter is advanced in the patient's vasculature until the distal tip of the guiding catheter is seated in the ostium of a desired coronary artery. A guidewire is first advanced out of the distal end of the guiding catheter into the patient's coronary artery until the distal end of the guidewire crosses a lesion to be dilated. A dilatation catheter, having an inflatable balloon on the distal portion thereof, is advanced into the patient's coronary anatomy over the previously introduced guidewire until the balloon of the dilatation catheter is properly positioned across the lesion. Once properly positioned, the dilatation balloon is inflated with inflation fluid one or more times to a predetermined size at relatively high pressures so that the stenosis is compressed against the arterial wall and the wall expanded to open up the vascular passageway. Generally, the inflated diameter of the balloon is approximately the same diameter as the native diameter of the body lumen being dilated so as to complete the dilatation but not overexpand the artery wall. After the balloon is finally deflated, blood resumes through the dilated artery and the dilatation catheter and the guidewire can be removed therefrom.
In such angioplasty procedures, there may be re-stenosis of the artery, i.e. reformation of the arterial blockage, which necessitates either another angioplasty procedure or some other method of repairing or strengthening the dilated area. To reduce the restenosis rate of angioplasty alone and to strengthen the dilated area, physicians now normally implant an intravascular prosthesis, generally called a stent, inside the artery at the site of the lesion. Stents may also be used to repair vessels having an intimal flap or dissection or to generally strengthen a weakened section of a vessel or to maintain its patency. Stents are usually delivered to a desired location within a coronary artery in a contracted condition on a balloon of a catheter which is similar in many respects to a balloon angioplasty catheter and expanded within the patient's artery to a larger diameter by expansion of the balloon. The balloon is deflated to remove the catheter and the stent left in place within the artery at the site of the dilated lesion.
In rapid exchange type balloon catheters, the catheter has an inflation lumen extending from the proximal end of the catheter to a balloon on a distal shaft section, a distal guidewire port at the distal end of the catheter, a proximal guidewire port located distal to the proximal end of the catheter, and a relatively short guidewire lumen extending therebetween. One difficulty has been forming a rapid exchange junction at the proximal guidewire port which is flexible, yet kink resistant and rugged, while maintaining collapse resistance. Some conventional designs have employed reinforcing layers or stiffening wires bridging the rapid exchange junction to prevent kinking at the junction between the proximal and distal sections. Reinforcing coils embedded in the polymeric tubular members of the shaft, such as for example in an inner tubular member defining a guidewire lumen, provide increased collapse resistance. Despite these attempts, prior art designs have suffered from various drawbacks. For example, one difficulty has been preventing embedded reinforcing coils from protruding through the polymeric layers of the shaft tubular member during assembly of the shaft. Accordingly, it would be a significant advance to provide a catheter having an improved catheter shaft junction between shaft sections such as the proximal and distal shaft sections. This invention satisfies these and other needs.